Question

A object of mass $M$ and radius $R$ is performing pure rolling motion on a smooth horizontal surface under the action of a constant force $F$ as shown in figure. The object may be

• A. disk
• B. ring
• C. solid cylinder
• D. hollow sphere

Answer 1

Answer: (B)

ring

For translational motion only, $F=ma$ ..........(1)

Torque about O, $\tau =I\alpha ⟹FR=I\alpha$

Also $a=R\alpha$ (pure rolling)

$⟹F{R}^2=Ia$ .............(2)

From (1) and (2), $F=m\frac{F{R}^2}{I}$

$⟹I=m{R}^2$

Hence its a ring.